FAQ: When is the best time to add compost?

Anytime is a good time to add compost.  Fall, spring, mid-season – every growing space can benefit from the boost of soil microbes and organic matter.

Is one timing option better than another?

A quick scan of gardening articles and blogs seems to indicate a slight lean toward fall.  Putting growing spaces to bed for the winter under a layer of compost and leaves gives soil microbes plenty of time to prep the ground for spring planting.

But incorporating compost a couple of weeks prior to seeding or transplanting at the start of the growing season works well, too.

No time to wait those extra 14 days?  Go ahead and add compost to the soil at planting time.  Just make sure that compost is fully mature.  (It should smell “earthy,” like soil from the forest floor.)  An immature product could compete with seedlings for nutrients or even burn young plants.  An unpleasant, ammonia odor is a telltale sign of immaturity.

If the compost at hand is still a bit too fresh, incorporate some air by turning with a shovel.  Dumping a bag onto a tarp or into a wheelbarrow will add air, as well.  Let it sit a couple of days, then check progress.  Keep “fluffing” the compost until it’s ready for use.

And don’t forget to add a bit of compost to container mixes, backfill, and other non-crop uses.  Follow manufacturer instructions, especially about amounts to use.  Depending on the feedstocks that make up the blend, some compost products may be richer than others.  Here’s the link to McGill’s use recommendations.

Most plants will welcome a little mid-season pick-me-up, too.  Simply sprinkle a little compost on top of a container’s soil layer, use as a side-dressing for row crops, or add a dusting over lawns.  Water in or lightly rake.